CuCo2O4 supported graphene quantum dots as a new and promising catalyst for methanol oxidation reaction

Recently, the design of an active electrocatalyst with a unitary structure and high electrocatalytic performance as an efficient and low-cost electrode material has received enormous attention in improving the performance of energy and storage devices. In this study, flower-like CuCo2O4 nanorods are synthesized through the hydrothermal method followed by calcination. Then, CuCo2O4 is hybridized with graphene quantum dots (GQDs) prepared by the pyrolysis method. The structure and morphology of the synthesized electrocatalysts are analyzed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction methods. The electrochemical performance of the prepared materials supported on a glassy carbon electrode is investigated by cyclic voltammetry at different methanol concentrations and various scan rates. Also, chronoamperometry and electrochemical impedance spectroscopy techniques are performed for the evaluation of stability and conductivity. The GQD/CuCo2O4 exhibits a good electrochemical surface area of 19.25 cm2 in 1 M KOH and 4 M methanol. Also, GQD/ CuCo2O4 shows a higher current density for methanol oxidation reaction (MOR) than CuCo2O4. The superior electrochemical performance of the GQD/CuCo2O4 can be attributed to the strengthening of the CuCo2O4 nanoparticle structure by a large electrochemically active surface associated with nanoporous morphology in the presence of GQDs. Besides, GQDs enhance the catalyst's performance by increasing electrical conductiv-ity and specific surface area.

Automated summary

Recently, there has been significant attention on designing an active electrocatalyst with a unitary structure and high performance to improve energy and storage devices. In this study, flower-like CuCo2O4 nanorods were synthesized through hydrothermal and calcination methods and hybridized with graphene quantum dots (GQDs) prepared by pyrolysis. The electrocatalysts were analyzed using various characterization techniques, and their electrochemical performance was evaluated. The GQD/CuCo2O4 showed a higher electrochemical surface area and current density for methanol oxidation than CuCo2O4, which can be attributed to the strengthening of its structure and increased electrical conductivity and specific surface area.